As electronic technology has advanced, the need for easily manufactured, inexpensive, smaller printed circuit board mountable transformers capable of providing power to the circuit board as well as sensing current in the primary circuit has increased. In order to provide power to the circuit board, the transformer core must have a high magnetic permeability and the coil must have a high number of wire turns to provide the required voltage. The toroidally wound transformer has generally been the best choice for such a transformer due to its accuracy and compact construction. However, the toroidally wound transformer involves a slow expensive winding process. Less expensive alternatives to the toroid transformer, such as two piece C or E-shaped laminated core transformers or interleaved laminated core transformers, have air gaps in their cores which interrupt the flow of magnetic flux in the core and therefore reduces the accuracy of the transformer. Using special materials having high permeability and proper alignment of the material grain can reduce the interruption of magnetic flux flow in the core but significantly increases the transformer cost. Another alternative is to use a continuous lamination or close magnetic core. This will eliminate the air gap problem but requires winding of the coil about one leg of the closed core. Providing a coil with enough turns to produce the voltage required to power the circuit board can then become a problem. If a fine wire is not used for the coil the number of turns needed to produce the required voltage will significantly increase the physical size of the transformer and thus prohibit mounting on the printed circuit board. High speed winding of a fine wire coil about a one piece bobbin is not new. However, the one piece bobbin construction must be used on a two piece C or E-shaped transformer core or an interleaved lamination core. These cores have the air gap problem. The more desirable solution would be to wind a fine wire core about the leg of a continuous lamination or closed magnetic core. This process is available but has generally been limited to larger power transformers having coils consisting of relatively few turns of medium gauge wire or ribbon wire which must be wound at slow speeds. Examples of this process may be found in U.S. Pat. Nos. 2,305,999; 2,414,603 and 3,043,000.
In recent years the transformer industry has begun to wind coils about continuous lamination cores or closed magnetic cores of smaller transformers. However, as seen in U.S. Pat. Nos. 4,325,045; and 5,515,597, bobbin positioning and low winding speeds have restricted the efficiency of this winding process. All of the transformers described above involve a number of labor intensive subassembly steps and provide no means for simultaneously terminating the coil wire and connecting to the printed circuit board. It would therefore be desirable to have a less labor intensive generally automated method of producing a low cost, accurate, small, printed circuit board mountable transformer having a high speed spin wound fine wire coil on a continuous lamination or closed magnetic core.